The Iranian army said it had attacked U.S. military equipment depots at Al-Adiri, latterly named Camp Buehring, in northern Kuwait, and the positions of U.S. troops at Camp Arifjan and at Camp Doha, near Kuwait City.
Iran's Revolutionary Guards said they had significantly damaged a surveillance tower used by the U.S. Fifth Fleet in Bahrain.
U.S. airstrikes hit Piranshahr, in West Azerbaijan Province near Iran's border with Iraq, at 9 a.m. (0530 GMT) on Friday, damaging several vehicles, according to the province’s emergency services, quoted by Iranian media.
U.S. missiles struck a Revolutionary Guards Navy headquarters in the Ziba Kenar area of the Caspian Sea province of Gilan, according to a security official in Gilan quoted by Iranian media. Gilan provincial authorities said U.S. projectiles had also struck the port city of Bandar Anzali, according to the ILNA news agency.
Four people were killed and five injured in a U.S. missile attack on the Iranian city of Ahvaz, state broadcaster IRIB said.
In a statement carried by Iran's Fars news agency, the Revolutionary Guards warned the public in the Gulf countries of potential strikes against U.S. military personnel who may be using "buildings in cities as locations to direct their crimes".
It told people to "immediately move away from areas within a 500-metre radius of covert and hidden locations used by U.S. military personnel".
Since the U.S. and Israel began the war in February, Iran has demonstrated that it can hit U.S. targets in the region, even though Trump said early on that the U.S. had wiped out Iran's military capabilities.
Four people familiar with U.S. intelligence said Iranian strikes on CIA targets in the Gulf earlier in the war had prompted U.S. intelligence to investigate whether Russia was assisting Iran with targeting information or drone technology. The Kremlin on Thursday declined to comment on the report.
High oil prices are fuelling inflation globally, putting Trump's Republican allies under pressure ahead of midterm congressional elections in November.
The Republican-led U.S. House of Representatives backed legislation on Thursday directing Trump to halt U.S. military action against Iran, its latest rebuke of the president. Congress alone has the power to declare war under the U.S. Constitution.
Repeated similar resolutions passed in recent months have not led to cessation of the war. The Senate voted hours later to block a separate, similar measure.